[gst-devel] windows based live editing software

Sat Nov 17 11:06:15 CET 2007

Hi,

  After going a few times through your mail I couldn't find any
questions. So I'm going to suppose you want to know if this would be
possible with GStreamer (else I'm wondering why you posted this here)
and what directions you should start looking into.

On Fri, 2007-11-16 at 11:24 +0100, Juergen Thiel wrote:
> Hello from Leipzig,
>  
> I am a media science student and I'm planning an online TV station. I
> got my first experience with internet tv broadcasting on TVU. I
> started off with Windows Media Encoder and VLC but soon realized  that
> both have advantages.
>  
> PLUS
> WME - you can switch between source files in contrast to VLC
> VLC - you can edit your output stream much better
>  
> Than I discovered DVmixer PRO. It can switch between short streams and
> source files WITH transition and has a built-in title generator and a
> GREAT automation tool. A similar chinese copy-cat software (vj -
> something) can do the same. The software would be perfect if it would
> support 3 more features and if it wouldnt take up soooo much CPU-power
> after a minute.

   If I understand correctly, you want to be able to do a "live video"
software mixer, with a few extra bells and whistles.
   I'm not sure anyone has tried this in GStreamer yet, but let's break
up what's needed to do this:

  * live video input : GStreamer 'can' read streams for webcams
(v4l(2)), cameras (dv1394src), microphones/audio input (alsa/oss),
RTP/RTSP streams, voice/video over ip (udp/rtp...), mms:// streams
(mmssrc/asfdemux/wm[av] decoders), http streams. All those sources
aren't equal though. Some offer REAL live input (hardware sources and
RTP/UDP) which won't introduce too much latency, whereas some other
(http, mms, rtsp/tcp, files) might require a substantial amount of
buffering before being able to produce a 'live' stream.

  * live video output : hardware outputs (screen, soundcard), rtp/udp.
Although if you want to broadcast, you will need an additional software
like flumotion for example.

  * mixing : we have simple audio (fade) and video (blend) mixing
elements in GStreamer. They might require a bit of testing for latency.

  * scaling : you will need to make sure your output audio/video stream
have the same width/height/rate/depth/... You will therefore need some
transformation elements we have in gstreamer (audioconvert,
audioresample, videoscale, videorate).

  And then obviously your code to wrap all of this together.

>  
> MISSING FEATURES of DVmixer PRO
> - source file support for mms://*- http//*-streams and playlists (asx,
> m3u)
  we have this in GStreamer

> - can't handle long streams

  What do you mean by long streams ? What happens ? 

> - it should have split screen features

  That should be doable using the smpte mixing elements, but those
require some more work currently.

>  
>  If I use the tinyurl-website to make the mms-urls (I  entered http to
> make it work of course) small... I get small urls that work. PROBLEM:
> it doesn't work to combine / switch between streams of a different
> rate - lets say, to switch from
>  
> mms://a1486.l1190850125.c11908.g.lm.akamaistream.net/D/1486/11908/v0001/reflector:50125
>  
> to
>  
> mms://stream10.streaming.prosiebensat1.net/N24_Live

  Those two streams work in GStreamer. But as I said above, they will
have to be already buffered in order to be able to switch as fast as
possible.

>  
> RESULT: the thing takes 100% of the CPU until it crashes - especially
> if I run TVU Broadcast at the same time in order to get the channel on
> TVU.

  Video processing CAN take a lot of CPU/RAM . If it takes too much...
you'll have to move broadcasting to another machine.

>  
> Another thing the programme should be able to do is to do this:
>  
> http://www.medialooks.com/products/directshow_filters/videomixer.html
>  
> like on the big news channels.
>  
> I found no video editing software that will
> - let you input streams incl mms-streams and asx-files
> - switch between them
> - can do animated background with split-screen using live feeds
> (streams)
>  
> It also should 
> - be able to work wih Inscriber InStream plug in or should have its
> own title genereator.with *.tga, cg-files, *.png, plus video- and
> alpha-channeled animation overlay. 
> - be able to play Scala InfoChannel (made with software frpm
> scala.com) files
> - have an automation segment.

  Except for the first two items (mms and switch), all the other items
will need to be written.
  For transitions and integration of other softwares, you will have to
write some GStreamer elements that do that. For the proprietary software
integration you are looking at a LOT of work unless they provide some
kind of public API/SDK that allows you to get the output.

  I hope this helps, nice idea,

     Edward

>  
> RESOURCES:
>  
> http://www.vanillaon.com/index.php?goURL=/products/mp_main.php
> DV Mixer Pro - if you want the un-demo-ed version in order to take it
> apart I can send you the files to make it a full version.
>  
> http://www.medialooks.com/products.html
> On the medialooks site they have direct show filters and objects for
> mixing and automation.
>  
> http://www.broadcast.harris.com/inscriber/instream/
> Inscriber Instream and many infos about titling-software
>  
> http://www.convid.com/la/?gclid=CPXKz57yyI8CFQI5aAodN26H-Q
> another stream title generator
>  
>  
> Best wishes,
> Juergen in Leipzig
>  
>  
>  
>  
> -----------------------------------------------
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> 04177 Leipzig
> Germany
>  
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